Split case submersible pump



April 2, 1968 F. B. EASTON SPLIT CASESUBMERSIBLE PUMP 9 Sheets-Sheet 1Filed Jan. 24, 1967 FIG.I

INVENTOR. FRANK B. EASTON April 2, 1968 F. B. EASTON SPLIT CASESUBMERSIBLE PUMP 9 Sheets-$heet 2 Filed Jan. 24, 1967 FIG. 5

INVENTOK FRANK B EASTON OAL\ NEYS l April 2, 1968 F. B. EASTON SPLITCASE SUBMERSIBLE PUMP 9 Sheets-Sheet 5 Filed Jan. 24. 1967 H6. IO

INVENTOR. FRANK B. EASTON 7 A TORNEYS April 2, 1968 F. a. EASTON3,375,739

SPLIT CASE SUBMERSIBLE PUMP Filed Jan. 24, 1967 9 Sheets-Sheet 4 FIG. u

FIG. I 4

INVENTOR. FRANK B. EASTON FIG. 16 W ATT RNEYS F. B. EASTON SPLIT CASESUBMERSIBLE PUMP April 2, 1968 3 MN m To 1% WT A vm S WE t MW 8 mm K N 9A Du F Filed Jan. 24 1967 108' M 744%, 5: 8nd

ATTORNEYS April 2, 1968 F. B. EASTON SPLIT CASE SUBMERSIBLE PUMP ' 9Sheets-Sheet (-1 Filed Jan. 24, 1967 F I G. 23

INVENT FRANK B.

- ll IIL OR. EASTON ATTORNEYS F. B. EASTON April 2, 1968 SPLIT CASESUBMERSIBLE PUMP 9 Sheets-Sheet 7 Filed Jan. 24, 1967 INVENTOR; FRANK B.EASTON ATTORNEYS F. B. EASTON April 2, 1968 SPLIT CASE SUBMERSIBLE PUMP9 Sheets-$heet H Filed Jan. 24, 1967 FIG.27

3| FIG. 30

INVENTOR FRANK B. EASTON ATTORNEYS April 2, 1968 F. B. EASTON SPLIT CASESUBMERSIBLE PUMP 9 Sheets-Sheet 9 Filed Jan. 24, 1967 RN NS 1 WA m i 8 K"HHU F M. HW

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MW, mm, a aw ATTORNEYS United States Patent 3,375,789 SPLIT CASESUBMERSIBLE PUMP Frank Bernard Easton, Salem, Ohio, assignor to CraneCo., New York, N.Y., a corporation of Illinois Continuation-impart ofapplication 'Ser. No. 390,677, Aug. 19, 1964. This application Jan. 24,1967, Ser. No. 611,453

Claims. (Cl. 103-402) ABSTRACT OF THE DISCLOSURE The disclosure pertainsto the art of multistage centrifugal pumps and more particularly to sucha pump having a casing formed of at least two longitudinal sections eachmolded from an epoxy or other plastic material. The casing sections arebrought together to define pumping stages around a single rotatablespindle assembly of impellers. Fastener elements more rigidlongitudinally than the casing sections secure the sections together ina manner designed to straighten the pump and align the stages With theimpeller spindle axis.

This application is a continuation-in-part of US. application Ser. No.390,677 filed Aug. 19, 1964, now abandoned.

This invention pertains to multistage centrifugal pumps and moreparticularly is applicable to a multistage submersible pump in whichtheentire pumping unit, including the motor, is completely submerged ina liquid which is to be. pumped. Although the invention will bedescribed with particular reference to such a pump, it is equallyapplicable to other types of pumps employing linear pumping stageswhether submersible or not.

Multistage centrifugal pumps conventionally have a linear series ofpumping units or stages each of which includes a diffuser with arotatable impeller mounted therein driven from a common drive shaft. Theshaft extends lengthwise in the pump and is supported at its oppositeendsby bearings. With such a construction --it is essential to maintainrigid manufacturing tolerances if the diffusers and impellers in eachstage are to rotate freely relatively to each other; this problem iscompounded in certain modular multistage pumps where one stage isstacked upon the next in a vertical array. As a result, manufacturingtolerances are multiplied and over the length of the pump, create astacking limit condition restricting the number of pumping stages whichcan be put together without producing a binding condition inthe'uppermost stages. As a result, it frequently occurs that a costlyand time consuming run-in period is required while the adjacent surfacesof the impellers and diffusers accommodate each other by mutualabrasion.

Another problem with multistage pumps is the require ment for precisealignment of the diffusers and impellers. This requirement is especiallydifficult to meet with pumps having parts which are molded separatelyand then assembled. In order to assemble the parts while preserving theaxial alignment between the pumping stages and avoiding interferencebetween rotating and nonrotating parts, particularly plastic parts,loose tolerances are permitted. This is objectionable because it resultsin a loss in pressure head due to a leakage between stages requiring anexcessive number of stages to compensate.

Also, experience has shown that the stringent requirements for pumpingstage alignment are not achieved with one piece plastic pump casingssince it is difficult to prevent warpage upon removal of the casing fromthe manufacturing molds.

The present invention contemplates a new and im 3,375,789 Patented Apr.2, 1968 proved multistage centrifugal pump having a molded casingstructure adapted to overcome the above mentioned difficulties andothers.

In accordance with the invention, a multistage pump is provided whichincludes a series of pumping stages. Each stage comprises animpellerwhich discharges into a volute passage for circulating fluid tothe next stage. A drive member interconnects the impellers of each stagefor transmitting a torsional driving force from one to the other. A pumpcasing is formed of at least two longitudinal sections which are fittedtogether around the stages in mating fashion on opposite sides of amutual parting plane. And fastener elements, more rigid. longitudinallythan transversely, are engageable at the parting plane of two sectionsfor holding them together and in substantial alignment with the axis ofthe impeller.

More particularly, where each volute passage is part of a diffuser whichis separable as a unit from the pump casing, each longitudinal casingsection includes a plurality of radially opening pockets defined byaxially spaced arcuate segments, the pockets independently supportingeach diffuser in proper relationship to each impeller.

In accordance with a further aspect of the invention, and particularlyin order to achieve closer running clearances between the impellers anddiffusers, the impellers are arranged on a common shaft as a singlerotating spindle assembly and the diffusers are split with each halfbeing molded or otherwise affixed integrally into the pump casingsections so that upon assembly thereof, the impeller spindle assembly isrotatably supported in precision alignment 'with a minimum of runningclearance between the rotating and nonrotating parts.

Further in accordance with this aspect of the invention, where the molddraft necessary for withdrawal of the manufacturing molds in making thediffusers integral with the casing sections is not conducive to properdiffuser volute passage configuration, partial diffuser sections aremolded integrally so that when assembled, the casing sections cometogether to firmly support the impeller spindle assembly and removablediffusers inserts are fitted with each partial diffuser section tocomplete the diffuser volute form. t.

A principalobject of the invention is to provide a new and improvedmultistage centrifugal pump which is simple in construction, economical.to manufacture and can be assembled from molded casing sections fittedtogether in complementary fashion.

Another object'is to providea pump casing as referred to above whichmaintains precise clearance and alignment between diffusers andimpellers, thereby increasing pumping efficiency.

A further object is to provide that the diffusers are molded orotherwise affixed into the casing sections so that a single spindleimpeller assemblymay bezused there by reducing the .running'tolerancebetween rotating and nonrotating parts.

.Another object is the provision of a multistagecentrifugalpump casingformed from duplicate sections capable of being molded by injectionorcompression molding techniques in a single mold.

Still another object is to provide a pump casing as referred to above inwhich any warpage due to the manufacturing process is corrected bystraighteningthe casing as the sections are joined together;

Other objects andfeatures of the invention will be more apparent from aconsideration of the following descripinventive pump casing and onefastener element therefor;

FIGURE 3 is a partial longitudinal sectional view of the pump takenalong line 3-3 of FIGURE 1;

FIGURE 4 is an enlarged fragmentary transverse sectional view takenalong line 44 of FIGURE 1;

FIGURE 5 is an enlarged end view of a fastener element in the unmountedcondition as seen approximately along the line 5-5 of FIGURE 2;

FIGURE 6 is an enlarged fragmentary view of the longitudinal casing sealtaken approximately along line 6-6 of FIGURE 4;

FIGURE 7 is a cross-sectional view taken along line 77 of FIGURE 6;

FIGURE 8 is a cross-sectional view taken along line 88 of FIGURE 3;

FIGURE 9 is an offset cross-sectional view taken approximately alongline 9--9 of FIGURE 3;

FIGURE 10' is a cross-sectional view taken along line 10-10 of FIGURE 3;

FIGURE 11 is a pictorial view depicting the inventive pump casing in agreatly exaggerated wraped condition prior to assembly of the fastenerelements;

FIGURE 12 is a sequential view depicting the relative position of thefastener elements and easing at an intermediate stage of assembly;

FIGURE 13 is a final assembly view showing the Warped condition of thecasing corrected;

FIGURE 14 is a fragmentary view of the casing showing the use ofadjustable sealing members between pumping stages as an alternative tothe preferred embodiment of the invention;

FIGURE 15 is an enlarged fragmentary view of an alternative arrangementof the longitudinal casing seal;

FIGURE 16 is a view taken along line 1616 of FIGURE 16; and

FIGURE 17 is a fragmentary view of another alternative arrangement ofthe longitudinal casing seal.

FIGURE 18 is an exploded perspective View of the right half of a pumpcasing modification in accordance with the invention in which thediffuser sections are molded integrally therewith;

FIGURE 19 is a partial, cross sectional assembly view of this pumpmodification;

FIGURES 20-23 are cross sectional views taken along the section lineswhere indicated in FIGURE 19;

FIGURES 24-26 show a further modification in which the diffuser sectionsare partly molded in the casing and partly formed by removable inserts;

FIGURES 27-29 show a further modification using removable inserts;

FIGURES 32 show still another pump modification where the diffusersections are cemented into the casing sections; and

FIGURES 33-34 are exploded views of the pump assembly method accordingto the modification in FIG- URES 30-32.

Referring generally to the drawings wherein the showings are for thepurpose of illustrating certain embodiments of the invention only andnot for the purpose of limiting same, FIGURES 1-3 show a pump 10including an elongated casing 12 having an inlet 13 and an outlet 14. Alinear series of pumping units 15 in the casing 12 each include animpeller 16 and a diffuser 17. Each impeller 16 is driven by shaft 18from a motor 20 protec tively encased in a sealed cannister 22. Thosefamiliar with pumps of this type will recognize that the embodimentshown relates to a submersible pump of a type commonly used in domesticwater systems which have a storage tank above the ground and a wellwhich extends down into the ground to provide a source of water. Thesubmersible pump 10 is lowered, motor first, until it is completelysubmerged in the well water. The outlet 14 of the pump is connected tothe storage tank and suitable above ground controls are provided foroperating the system.

Referring now to the drawings in more detail, it is 4 noted in FIGURE 1that the casing 12 is actually divided into two half sections.' Alefthand section 24 mates with a substantially duplicate right handsection 26 with like parts of one section joining with like parts of theother in complementary fashion in a common parting plane at 27 throughthe axis of the pump. Where appropriate, the description will be onlywith reference to the right hand half section 26 and it will beunderstood that it applies equally to the other section 24 and likenumerals will be used to indicate like parts in each section.

In accordance with the invention, the section 26, as shown best inFIGURES 2 and 3, has a plurality of archshaped cavities or pockets 28defined by axially arcuate segments or ribs 30 which project radiallyinwardly and terminate in semi-circular surfaces 32 aligned with thepump axis. Each rib 30 has a planar surface 34 facing the motor end ofthe pump which merges in a smooth curve with a surface 35 terminating ina shoulder 36 on the next adjacent rib 30. Each diffuser 17 has aradially extending wall 42 with an inner hub 43 aligned with the pumpaxis. Vanes 44 which join to the wall 42 curve radially inwardly, asshown best in FIGURE 9, and are configured on the outer edge 45 so as tonest with the continuous surfaces 34, 35 of the pockets 28 thus definingvolute passages 46 which open into pumping chambers 48 surrounding eachimpeller 16. Diffuser locating tabs 41 which project from the surfaces35 engage the vanes and prevent rotation of the diffusers. Volutepassages 46 thus provide fluid communication from one impeller to thenext. It should be noted that each diffuser 17 is independently andremovably supported within its associated pocket 28 isolated from thenext diffuser in the series.

As shown in FIGURES 3 and 9, a more or less conventional impeller 16 isprovided having a hub 54 received on the shaft 18 being adapted torotate conjointly therewith. A front plate 56 is joined to a rear plate58 by curved blades 59 defining radially outwardly curved passages 60which communicate with an intake eye 62. The rear plate 58 has anaxially extending collar 64 which preferably has a machined outersurface 66 concentric with the arcuate surfaces 32 on the ribs 30. Theradial clearance spacing between the surfaces 66 and 32 is preferablyonly a few thousandths of an inch to provide a relatively effectivefiuid seal. As an alternative, the ribs 30 may be provided with loosefitting circular nibs 68, as shown in FIGURE 14, having resilient sidewalls 69 for engaging the ribs 30 so as to provide a yieldable sealingsurface 70 for sealing with the surface 66 of each impeller 16. Withthis alternative sealing arrangement, axial alignment between stages issomewhat less critical since the nibs '68 can adjust to compensate forslight amounts of axial deviation. In a modification describedhereinafter, precision clearance and alignment is more certain and nibs68 may be eliminated.

Referring to FIGURE 3, the impellers 16 are stacked one upon the otheron the shaft 18 in a linear series with the hub 54 of one impellerresting against the hub 54 of the next. The first stage impeller closestto the motor 20 rests against a spacer sleeve 71 for determining theproper longitudinal position of the whole impeller series with respectto the pockets 28. Axially beyond the spacer sleeve 71, the shaft 18 isprovided on its end with a splined sleeve 72 coupled with a splined stubshaft 74 driven by the motor 20 by means of a coupling 75 rotatablyreceived in bore 78' of the casing 12. At the opposite end, the shaft 18carries a bearing journal 80 tightened down against the uppermostimpeller 16 by means of nuts 82 threaded on the end of shaft 18. A guidetube 84' supported in a contoured web 85 projecting from the casingsections 24, 26 is provided on the upper end of the impeller assembly.The guide tube 84 is clinched over at the lower end 86 to hold theuppermost diffuser 17 in proper relation to the uppermost impeller 16.When the two half sections 42, 26 are assembled, the arcuate pockets 28in each section are fitted around the diffusers 17 and impellers 16 ofeach pumping stage. The diffusers are positioned to register with thediffuser locating tabs 41. Bolts 90 hold the casing sections togethersecurely in the region where the impeller assembly is coupled to themotor 20 and bolts 92 near the upper end of the casing insure a rigidjoint where the contoured web 85 supportingly engages the guide tube 84of the impeller assembly. Pins 94 extending between the upper and lowerhalf sections 24, 26 may be used to insure proper longitudinalregistration of the two sections. The motor 20 and cannister 22 aresupported from the lower end of the pump casing by bolts 105 and a powercable 106 for motor 20, suitably insulated with a water repellentmaterial, connects to an above-ground control and source of electricalpower not shown.

' In accordance with one aspect of the invention, a seal is providedbetween the assembled half sections 24, 26 when the mating faces of thetwo sections are not smooth enough to seal or when the pressure is veryhigh. The seal includes a pair of elastomeric cords 96 which arepositioned in grooves 98 formed in the mating face of the section'26 onopposite sides of the pump axis as best shown in FIGURES 3, 4', 6, and7. Each groove 98 receives a cord 96. Both cords 96 form a sealingenvelope in the parting plane 27 of the pump casing 12 around thepumping stages from the pump inlet 13 and the pump outlet 14.Alternatively, the elastomeric cords 96 may include radially inwardlyextending finger portions 95 received in grooves in the mating faces ofribs 30 as shown in FIGURE 17 thus sealing between each pumping chamber48. Shown greatly enlarged in FIGURES 6 and 7, small crescent shapedprojections 99 periodically spaced along each groove 98 serve to holdeach cord 96 in place by compressing a small portion of it. Moreimportantly, the projections 99 prevent a longitudinal flow of liquiddown the pump which would create a substantial leak at highpressures..For the same reason, the cords 96 may also have extensions101 exposed in a surface ground area 102 of the casing as shown inFIGURES 15 and 16. A relief valve 103 in the outlet 14 has an O-ring 104which sealably engages the surface ground area 102 as shown in FIGURE 3,but where in the alternative, extensions 101 are used, they cooperatewith the O-ring to provide an effective seal in the pump seam at thislocation. A modified relief valve and seat arrangement will be describedhereinafter which is designed to seat more uniformly and permit ashorter pump.

The manner in which the casing sections are secured together will now bedescribed. In accordance with the invention, each casing section 24, 26is provided with a longitudinal groove 107 on opposite sides of theparting plane 27. As shown in FIGURES l, 2, and 4, each groove 107 ineach half section is inclined outwardly toward the motor end of the pumpand away from the parting plane 27 providing a tapered, molded structureor guide 108 bisected by the plane 27. A pair of tapered channels orfastener members 109 having clinched over edges 110 are slidablyreceived in the grooves 107. The back portion 111 of each channel 109 istransversely flexible and straddles the tapered guide 108, thus holdingthe casing half sections together in clip-like fashion. The channels 109have an additional function during the assembly of the half sections 24,26 which will be more fully explained hereinafter. 'At present, and inthis connection, it is noted that the grooves 107 are formed by arcuateshaped overhanging edges 112 of the guide 108 which face away from theparting plane 27 and the axes of the edges 112 coincide with the axes ofthe clinch bend edges 110 of each channel 109.

Before the channels 109 are inserted, the back portions 111 are in amore severely bowed condition as shown in FIGURE 5, and upon assemblywith the casing 12 are spread transversely to place a bending stresstherein thus taking a much more flattened cross-sectional appearancecomplementary to the molded structure 108 as shown in FIGURE 4. Channels109 and the molded structure 108 thus form complementary means on eachcasing section which when brought together define cooperating structurefor aligning the pumping stages and securing the pump together. In thepreferred form, the curvature of the back portion 111, rather than beinguniform, is more or less elliptical having a maximum radius at thecenter and decreasing on each side thereof to a minimum radius adjacentthe clinch bend edges 110. However, the channel members 109 must be asrigid as possible in an axial direction and are formed of a materialhaving a much higher modulus of elasticity than the material from whichthe pump casing 12 is formed. For example, a suitable material whichwould resist the corrosive environments of the pump and also provide thenecessary strength would be stainless steel.

Upon assembly, the impellers 16 and diffusers 17 are strung on the shaft18 and this assembly is placed in one of the sections 24, 26 of the pumpcasing 12 such that each diffuser 17 is properly located around itsassociated impeller 16 in a pocket 28. Upon assembly of the other casinghalf section, the guide tube 84 at the upper end of the impellerassembly is fitted between the mating complementary portions of the web85 while the opposite end is fitted within the bore 78. Prior to this,if found necessary, the sealing cords 96 and locating pins 94 are put inplace. Bolts and 92 are then inserted and tightened to maintain a slightpressure to hold the sections together. The casing 12 is then placed ina suitable holding fixture where it is to be straightened if necessary,as explained hereinafter.

Those acquainted with conventional submersible pumps will recognize thatthe basic pumping operation is such that liquid to be pumped is drawn inat the inlet 13 and is raised from one pumping stage to the next by thecentrifugal action of the impellers 16. The diffusers 17 conduct thefluid from one impeller to the next until it discharges under pressurethrough the outlet 14.

As mentioned before, in the past a stacking limit problem has beenencountered where each diffuser is stacked one upon the other. Toovercome this difiiculty in the present invention, the casing halfsections 24, 26 are molded as a unit so that the pockets 28 arenecessarily equally spaced. Thus when the diffusers 17 are assembled inthe pockets 28, each one will be independently supported and will not beaffected by the stacking tolerances of the preceding diffusers.

The rigid alignment and close running clearance required betweenrotating and nonrotating parts has also been a. problem in the past.Where the parts are formed from a thermosetting plastic material whichcan be molded under conditions of heat and pressure to take a permanentshape additional problems are encountered. Due to the molding operation,it is not uncommon for the plastic part to takea permanent set afterbeing extracted from the mold in a slightly warped condition which uponassembly results in a misalignment. Oversized tolerances are thusrequired to compensate.

Referring now to FIGURES 11-13, prior to inserting the channel members109, the casing 12 is in a warped condition and instead of beingstraight, follows some independent path determined by the permanent setofthe plastic material after removal from the mold. The condition ofwarpage is very slight in most cases but is greatly magnified in FIGURE11 for purposes of illustration. To straighten the casing 12 .and inaccordance with the invention, both channels 109 are started in thegrooves 107 on opposite sides of the casing 12 at the narrowest span ofthe tapered guides 108 as depicted in FIGURE 11. As the channels 109 aremoved simultaneously in an axial direction, the clinch bend edges 110bite into the groove 107 on each side of the guide 108 causing eachchannel back portion 111 to flex to a less tbowed condition thus placinga clamping force on the casing sections 24, 26.

Inaddition, as depicted in FIGURE 12, as the channel members 109 aredriven farther down the body of the pump casing 12 they begin to have aneffect on its warped condition tending to bring the casing into truealignment. This results from the fact that the channels 109 are as rigidas possible in an axial direction and have a very high modulus ofelasticity with respect to that of the thermosetting or thermoplasticmaterial from which the casing 12 is formed. The result is that whilethe channels 109 may flex transversely to provide a clamping force, theyare virtually rigid in a longitudinal direction so as to have astraightening effect on the casing 12. When fully inserted as shown inFIGURE 13, the casing will be aligned and the bolts 90 and 92 may betightened securely.

As previously noted, the curvature of the back portions 111 of thechannels 108 is preferably not uniform, but is actually elliptical inshape. As a result, increased clamping forces for holding the casingtogether are developed when the channels are fully inserted. Inaddition, the clinch bend edges 110 have a radial center coincident withthe center of the arcuate edges 112 of the tapered guides 108. Thisinsures continuous contact between the clinch bend edges 110 and theedges 112 so that the straight condition of the channels 109 isaccurately imparted to the casing 12.

FIRST MODIFICATION Referring now to a modification of the invention inwhich similar parts will be identified by like numerals with theaddition of a prime mark, FIGURES 18-23 show a modified version of thesubmersible pump described hereinbefore in which the major differencesare (1) the diffusers are split in half and each half is moldedintegrally With the pump casing section, (2) the pump casing sectionsare joined throughout their length by channel members eliminating theneed for transverse bolts and (3) modifications of the relief valvearrangement and an improved inlet and discharge flow configurationpermit a shorter pump. The advantages arising from these and othermodifications will be apparent from the description.

Referring now in detail to FIGURES 18-23, the pump casing 12', as shownby the exploded right half 26' in FIG. 18, is shorter than the pumpcasing 12 (FIG. 2) by an amount X and is molded with diffuser halves 17'formed integrally therewith. To permit mold withdrawal, the diffuserhalves 17' differ from the diffuser 17 described earlier in that onlytwo cutwaters a, b (FIGURE 21) and volute return passages 46' perpumping stage are permitted. In addition, the volute return passages 46'are more of the side delivery type as depicted by the dotted lines inthe upper two stages in FIGURE 18 in which the flow configurationdiverges to the side from the outwater a, widening out at the impellerintake 62 of the next adjacent pumping stage. The chief advantage offorming the diffuser halves 17' integrally with the casing sections isthat a single impeller spindle S (FIG. 19) may be used without thediffusers being assembled around each impeller.

In accordance with this modification of the invention, the singleimpeller spindle S comprises an impeller shaft 18' upon which a seriesof impeller 16 are mounted and held as a permanent assembly by clinchnut 82. By single impeller spindle, the meaning is that the impeller 16and shaft 18' constitute a single rotating body which permits theimpellers 16' to be center ground on the axis of shaft 18'. As a result,the tolerances between the rotating and non-rotating parts may be heldto within a few thousandths of an inch thus providing a freely runningassembly with a minimum of leakage between pumping stages. In effect,closer tolerance means that a greater pressure head may be obtained witha fewer number of stages.

In the modification, better alignment of the stages is also obtained dueto the fact that the channel members 109' extend the full length of thepump thus eliminating the need for transverse bolts 90, 92 as shown inthe previous embodiment (FIGURES 8 and 10). As shown in FIGURE 19, thechannel members 109' and tapered guides 108' bridge across the pumpintake screen thus holding the casing sections together securely in theregions of greatest stress where the impeller spindle S is coupled tothe motor 20.

A further advantage in the modification is that the pump is shortened bythe distance X while providing for the same number of stages. This isachieved primarily through a modification of the pump intake 13, outlet14, and relief valve 103. Essentially the intake 13 is shortened withthe intake screen R molded directly in the casing halves.

At the outlet 14', the discharge configuration is through a vane head Qproducing a more globular transition structure which also supportssleeve P. The relief valve 103 is situated on sleeve P in closeproximity to the last stage of the puump and is vertically slidable onguides M (FIG. 20) to a limited free open position permitted by stops N.An O-ring 104 seals on a frustoconical continuous seat ring L whicheliminates the possibility of slight leakage due to a discontinuity atthe pump joint. The relief valve 103 is also less susceptible to cockingon the seat L due to the function of guides M. The relief valve sealsunder the influence of the static pressure head acting on it from above.O-ring 105' resiliently holds the seat L and seals at the joint betweenthe casing 12' and a relief valve bowl B. Return flow is trapped byO-rings 104, 105' sealing on the continuous seat L.

To permit the use of a single manufacturing mold for making both halfsections of the pump casing, the relief valve bowl B is formedseparately and joined to the pump casing by the use of cement or bytwist-lock lugtype fasteners 103a. Threads are thus eliminated whichwould require separate molds for each half 26'.

SECOND MODIFICATION Where a more perfect volute passage 46 is requiredthan can be obtained with the diffuser halves 17 formed integrally withthe pump casing, a further modification is shown in FIGURES 24-26. Inthis modification similar parts will be identified by the same numeralwith a letter subscript. In FIGURE 24 the pump casing 26a is molded withintegral diffuser partial half sections 17a to provide a more straightline withdrawal path for the molds. The partial half sections 17a,however, remain connected to the casing wall for substantial support andin this modification, the volute configuration 46a (FIG. 25) is, in partdefined by removable diffuser inserts positioned in the first and thirdquadrants of each pump stage.

THIRD MODIFICATION As an alternative, a further modification is shown inFIGURES 27-30 in which minimum width diffuser partial half section 17bare integral only at the center portion of each pump casing section 26bproviding even greater freedom of mold withdrawal. The form of thevolute passage 46b is not compromised due to the use of full sizedinserts 120 in each pumping stage. The inserts 120 may be held in placerelative to the diffuser section 171; by means of tongue and groovejoints 122.

FOURTH MODIFICATION Turning now to FIGURES 31-34, another modificationis shown in which diffuser half sections fit into pockets 28' of eachright and left hand section 24', 26', of the pump casing (FIG. 32) sothat when the two casing sections are brought together (FIG. 31) thediffuser half sections 170 mate at the parting plane through theimpeller spindle axis. The diffuser half sections 17b have the multiplevolute passages 460 of the first embodiment (FIGURE 9) to providemaximum flow. Prior to inserting each diffuser half section 170 in itspocket 28, an epoxy cement E is spread on the radial outer surfaces 45,of the diffuser vanes 44.

The right and left hand pump casing sections 24', 26, are assembledaround the impeller spindle S as shown in FIGURE 33. Assembly of thevalve spindle P, relief valve 103' and valve bowl B may then take place.While the cement E is still wet the next step is to drive on the channelmembers 109' which takes any warpage out of the casing sections 24', 26as discussed above, and aligns the diffuser half section 17c with theimpeller spindle axis. Just prior to the setting up of the cement E, theimpeller spindle S is given a few turns to assure freedom of rotatingand nonrotating parts.

Where the casing half sections 24', 26' are molded out of much highermodulus of elasticity material and are therefore less flexible and lesssubject to warpage, a modification of the above assembly method may beused to achieve even closer mechanical alignment. In this methodslightly larger than half section diffusers are glued in place andaccurately prealigned by a full bearing-borediameter mandrel (not shown)until the adhesive has set. Assembly may then proceed as referred toabove.

The joint between the right and left hand casing sections 24', 26' maybe sealed in the manner disclosed in the first embodiment in FIGURE 3,for example, where an elastomeric cord 96 is used, however, since thisrequires that a groove 98 be formed in one of the casing sections toreceive the elastomeric cord 96, a lap sanded joint is precluded. By lapsanded the meaning is that the two surfacesare worked with or withoutabrasives until a smooth surface-to-surface fit is achieved. Thus,,as analternative sealing arrangement and to eliminate sealing by means of anelastomeric cord, the'mating surfaces of each casing section 24', 26 canbe lap sanded and'brought flush together. A polyester sealant may beapplied if desired.

While the invention has been described with reference to severalembodiments, any one of which may be used to practice the invention,obviously modifications and alterations other than those suggested willoccur to those skilled in the art upon reading this specification and itis my in tention to include such modifications and alterations insofaras they come within the scope of the appended claims except insofar aslimited by the prior art.

Having thus described my invention I claim:

1. In a centrifugal pump having a series of pumping stages, theimprovement comprising a molded casing formed of at least twolongitudinally mating sections and complementary means including moldedstructure on each section on opposite sides of a mutual parting surface,which means when brought together, defining a longitudinal extendingcooperating structure for securing the casing sections together andlongitudinal extending faster means having resistance to longitudinaldeflection greater than said molded structure longitudinally engageablewith said cooperating structure whereby said casing sections are securedin axial alignment with said pumping stages.

2. The improvement according to claim 1 including a series of impellersarranged on a common shaft as a single rotating spindle assembly andsaid casing sections being brought together to define said pumpingstages around each impeller.

3. The improvement according to claim 2 wherein diffuser structure ofeach pumping stage is molded in each casing section and is broughttogether in mating comple' mentary fashion closely circumjacent therotatable impeller spindle assembly when assembling said sections.

4. The improvement according to claim 3 wherein the diffuser structureis separable in each casing section at least in part.

5. The improvement according to claim 4 wherein the separable diffuserstructure is an insertdefining, in part, a volute return passageway ofthe diffuser structure.

6. In combination with a centrifugal pump of the type having a pluralityof linearly stacked pumping units each of which includes an impellermember having an intake eye at its axis connected to radially outwardlyextending discharge passages therein and a diffusion member havingradially inwardly curved vanes forming a pumping chamber around saidimpeller member and drive means interconnecting each impeller member fortransmitting a torsional driving force from one to the other,

a casing adapted to be assembled in surrounding relationship to saidpumping units being formed of at least two longitudinal sections fittedtogether in mating complementary fashion on opposite sides of a mutualparting plane and each section being formed of a material having arelatively low modulus of elasticity securing means for joining saidsections in assembled fashion comprising a fastener member considerablylonger than it is Wide movable longitudinally relative to said mutualparting plane during assembly of said casing sections and being formedof a material having a higher modulus of elasticity than said casingsections so as to resist bending in a longitudinal direction duringassembly whereby the linearly stacked pumping units are simultaneouslyaligned on a common axis with the casing sections.

7. The combination as set forth in claim 6 wherein each saidlongitudinal section includes a plurality of radially opening pocketsdefined by axially spaced segments havmg aligned arcuate openingscircumjacent the intake eye of each impeller member, said pocketsindependently supporting each diffusion member in spacial relationshipto each impeller member and the adjacent diffusion members.

8. The combination as set forth in claim 7 wherein each diffusion memberis configured so as to nest in a pocket and defines with said segments apumping chamber around each impeller member.

9. The combination as set forth in claim 7 wherein each mpeller memberhas an axially extending hub defining its intake eye and said arcuateopenings closely surround said hub to provide a fluid seal between saidpumping chambers.

1t), The combination as set forth in claim 9 and in addltion comprisingradially adustable sealing nibs mounted 1n said arcuate openingsincluding an annular portion 1n sealing engagement with said hub andradially spaced from said openings.

1 1. The combination as set forth in claim 6 and in addltion sealingmeans positioned between the mating surfaces of said sections andextending longitudinally along the outer boundaries of said pumpingunits.

12. In a submersible pump of the centrifugal type having a plurality oflinearly stacked pumping units each of which includes an impeller memberhaving an intake eye at its axis connected to radially outwardlyextending discharge passages therein and a diffusion member havingradially inwardly curved vanes forming a pumping chamber around saidimpeller member drive means interconnecting each impeller member fortransmitting a torsional driving force from one to the other, theimprovement comprising a casing adapted to be assembled in surroundingrelationship to said pumping units being formed of right and left handlongitudinally extending molded sections fitted together in matingcomplementary fashion on opposite sides of a mutual parting plane, eachsaid section having a plurality of radially opening pockets defined byaxially spaced segments having 1 1 aligned arcuate openings circumjacentthe intake eye of each impeller member, each diffusion member beingshaped so as to nest in a pocket and define with said segments a pumpingchamber around each impeller member and securing means for joining saidsections in assembled fashion.

13. The improvement as set forth in claim 12 and in addition sealingmeans positioned between the mating surfaces of said sections andextending longitudinally along the outer boundariesof said pumpingunits.

'14. The improvement as set forth in claim 13 wherein said sealing meansinclude radially extending portions at intervals therealong positionedbetween the mating surfaces of said segments for sealing between saidpumping chambers. I

I 15. The improvement as set forth in claim 13 wherein said sealingmeans include grooves formed in the mating face of one of said sectionsextending longitudinally along the outer boundaries of said pumpingunits and elastomeric cords received in said grooves sealably engagingthe mating surface of said other section upon assembly.

16. The improvement as set forth in claim 15 wherein said elastomericcords and grooves include means for sealing against the passage of fluidlongitudinally within said grooves.

17. A two piece casing for a multistage submersible pump have aplurality of linearly stacked pumping elements each of which includes adiffuser and an associated impeller having an eye at its axis, saidcasing comprising,

right and left hand elongated casing sections, each molded as a separateunit and having axially spaced segments extending radially inwardlybetween adjacent pumping elements terminating in arcuate surfacescircumjacent the intake eye of each impeller, said sections being fittedtogether in mating complementary fashion on opposite sides of a commonparting plane with said arcuate surfaces defining a series of boresadapted to be in substantial alignment with the impeller axes,

guide means on opposite sides of the casing at the joint thereofextending longitudinally on opposite sides of the common parting planeand fastener means having a linear portion which is rigid in alongitudinal direction and flexible in a transverse direction receivedon said guide means for simultaneously joining said sections andaligning said bores.

18. A two piece casing as set forth in claim 17 wherein said guide meanscomprises,

linearly extending grooves, each inclined outwardly with respect to theparting plane and said linear portion of the faster'means havinglongitudinally extending edges received in said grooves inclined in thesame direction thereas.

19. A two piece casing as set forth in claim 18 wherein said grooves aredefined by linearly extending arcuate portions formed in said casingsections facing away from the parting plane, the edges of said linearportion being turned inwardly beneath said arcuate portion into saidgrooves.

20. A two piece casing as set forth in claim 19 wherein said fastenermeans linear portion is bowed outwardly in a transverse direction toprovide a clamping force acting through said arcuate portions.

References Cited UNITED STATES PATENTS 2,072,033 2/ 1937 Frohnert 1031082,366,964 1/1945 Howard 103102 2,457,142 12/1948 French 230--1302,474,077 6/1949 Trumpler 230-130 2,578,617 12/1951 Watson 230-1303,158,295 11/ 1964 Me Conaghy 103-102 FOREIGN PATENTS 25,391 1905 GreatBritain. 29,260 1909 Great Britain. 879,320 10/ 1961 Great Britain.104,248 2/ 1963 Netherlands.

40 HENRY F. RADUAZO, Primary Examiner.

